On the twelfth day, with only one loss still, Hikaru is to face against an undefeated Isumi. The latter becomes anxious after learning from Ochi that Akira is after Hikaru and goes into overtime. Despite this, Isumi begins to dominate the match until he accidentally makes a bad move while under pressure, but illegally changes it before passing the turn. Hikaru must decide whether to ignore the rules violation and finish the match or call Isumi out.